Spectroscopy Using Short-Path Surface Plasmon Dispersion

A miniature surface-plasmon based spectrometer is presented for both the near zone and the far zone. In the near zone four different experiments have been completed with this system. It will be shown that with 632, 614, 543, and 440 nm incident lasers upon the system there is good agreement between experimental and theoretical transmission spectra. This system is shown to provide transmission spectra of different broad band-pass, glass filters across the visible wavelength range with high stray-light rejection at low resolution. These spectra are compared to those taken with a commercial spectrophotometer. Spectra of solutions of the laser dye Coumarin 540A are also prepared with the solvent methanol. Absorption spectra of different concentrations of this solution are shown. The system can distinguish between the absorption of the different solutions used in the work. Lastly, an absorption spectrum of chlorophyll extracted from a spinach leaf is shown and compared to the spectrum obtained with a commercial spectrophotometer. Although this is not the first time this experiment has been set up, these are the first successful production of spectral data using the near field surface plasmon specrtrometer.

The surface plasmon spectrometer in the far field is also presented. This set up can similarly be used as a spectrometer or to determine the optical properties of materials by operation as a biosensor. Several initial test results and future ideas for this device are also presented.